Evacuating and gas charging apparatus



ObLZ, 1951 mm GRQAT' 2,570,103

EVACUATING AND GAS CHARGING APPARATUS I Filed July 16, 1946 4 Shoots-Sheet 1 I lrfi ven tor: f Charles 'F De Great,

b E15 Attorney.

Oct. 2, 1951 I c, 1' DE GRQAT 2,570,103

EVACUATING AND GAS CHARGING APPARATUS Filed Jul 16, 1946 4 Shoetahodt 2 Fig.2.

Inventor-i Charles T. DeGr-oat;

' H is 'Attornes.

9 C T. m: GROAT v 2,570,103

' zvAcuATpic AND GAS cnmcmc; QAPPAARATUS Q Filed July 16, 1946 4 Shoots-Sheet s Fig. 5a.

Inventor Charles T De G'roat His A'ctoPney Oct. 2, 1951 Filed July 16, 1946 c. 'r. DE G 6 T 2,570,103

EVACUATING AND GAS CHARGING APPARATUS 4 Sheets-Sheet 4 Inventdr": Charles T.DeGr-pat',

His Attorney.

Patented Oct. 2, 1951 EVACUATING AND GAS CHARGING APPARATUS Charles T. Dc Groat, Ballston Lake, N. Y., assignor to General Electric Company, a corporation of New York Application July 16, 1946, Serial No. 686,127

10 Claims. 226-206) 1 My invention relates to improved evacuating and gas charging apparatus, and particularly to apparatus of this type which is well adapted for the automatic manufacture of gas-filled elec- I tric discharge devices.

In my copending application S. N. 646,130, filed February 7, 1946, now Patent No. 2,565,298, issued Aug. 21, 1951, and assigned to the assignee of the present application, is described and claimed an automatic machine for the manufacture of electric discharge devices in which a plurality of stations are mounted on a rotatable support. Each station includes a vacuum pump and a compression fitting for connection with a discharge device to be evacuated. Communication between the low pressure side of the vacuum pump and the discharge device is controlled by a solenoid valve. The rotatable support is moved periodically into different operating positions where successive steps in the manufacture of the device are accomplished. The present invention is in the nature of an improvement on the apparatus described and claimed in my abovementioned application and relates particularly to an improved system of control for effecting the various steps of the manufacture in sequence as the movable support occupies successive positions, and for charging the device to a predetermined gas pressure. The system of the present invention is characterized by the flexibility with which the apparatus may be adjusted for different devices to be manufactured, and by the accuracy of the pressure to which the device is charged. The construction and arrangement of the parts of the apparatus are such that a minimum amount of gas is wasted in the charging operation, thus rendering the equipment particularly adaptable to the manufacture of devices employing a gas filling which is relatively expensive.

It is an object of my invention to provide new and improved evacuating and gas charging apparatus.

It is another object of my invention to provide a new and improved control system for charging an evacuated device to a predetermined gas pressure.

It is a still further object of my invention to provide new and improved apparatus for evacuating and gas charging electric discharge devices.

My invention will be better understood by relerence to the following description taken in connection with the accompanying drawings, and its scope will be pointed out in the appended claims. In the drawings, Fig. l is a plan view illustrating diagrammatically an automatic machine embodying my invention; Fig. 2 is an elevational view, in section, of one station or the machine shown in Fig. 1, and Figs. 3a and 35 considered together are a schematic representation of the control circuits employed at various stations of the machine shown in Fig. 1..

Referring now to Figs. 1 and 2 of the drawings. I have shown my invention embodied in an automatic exhaust and gas charging machine for the manufacture of electric discharge devices in which a rotatable support is provided with sixteen identical stations designated I to XVI, each provided with means for receiving a discharge device to be evacuated and charged with gas. In Fig. 2 is shown the details of construction of one of the stations (station XII) which, it will be understood, is duplicated at each of the remaining stations of the machine.

Referring now to Fig. 2, the machine comprises a stationary support or pedestal I upon which is mounted a rotatable support or turntable 2. The turntable 2 is provided with a peripherally extending flange 3 which provides a support for the evacuating apparatus of each of the sixteen stations. As illustrated, a vacuum pump designated generally by the numeral 4 is supported from the flange 3 by a suitable bracket 5. The pump may be any one of a. number of types well known in the art and to advantage may be of the oil diffusion type. As illustrated, the pump is: a twostage vertical type including two stacks 6 and l which terminate at the upper end of a boiler unit 8 within which the fluid of the pump is vaporized by means of a heater element designated by the numeral 8. The upper end of the conduit 6 provides the low pressure or intake side of the pump which is connected with an electric discharge device ID to be evacuated by a solenoid valve assembly II and a compression fitting l2. As illustrated, the solenoid valve assembly includes a conduit l3 which is supported from the upper end of the stack 6 by a fitting 14 which also provides a valve seat. The valve member 15 is movable in the conduit 13 and includes an armature I6 which cooperates with a valve-operating coil l1, positioned about the conduit 13.

The compression fitting I2 is provided at its upper end with a nut l8 which is rotatable to compress a suitable gasket (not shown) against the stem or tubulation of the discharge device IS. The body IQ of the compression fitting is supported from the conduit l3 by a bracket 2!! and is provided with a. central passage 2| which communicates with the upper end of the conduit I3 through a transverse passage 22. The vertical passage 2| extends below the transverse passage 22 andprovides a receptacle for pieces of glass or metal which accumulate in the fitting and which may be removed readily from the passage by removal of a threaded plug 23 received. in the lower end of the passage 2|. As illustrated in the drawings, the compression fltting and stacks 8 and I of the pump are provided with suitable passages and piping 24 through which cooling fluid may be circulated. The high pressure side of the pump 4 is connected with a stationary conduit 25 by means of a conduit 26 extending from the upper end of the stack 1 to the central portion of the turntable 2. As illustrated in the drawings, cooperating passages 21 and 21', formed respectively in the turntable 2 and pedestal I, provide a valve between the stationary conduit 25 and the movable conduit 26 for disconnecting the removable and stationary portions of the evacuating system during indexing of the movable support from one operative position to the other. As designated by the legend on the drawing, the conduit 25 connects with the rough vacuum system which, in accordance with established practice, may include vapor diffusion or mechanical pumps.

As a means for introducin gas into the electric discharge device after it has been evacuated, I provide a conduit 28 which communicates with the passage 2| in the compression fitting. The conduit 28 supports a tube 29 formed of a material which has the property of transmitting through its wall the gas with which the device is to be charged. If the charging gas is hydrogen, for example, the tube 29 is formed of palladium. The introduction of gas into conduit 29 is accomplished by subjecting the palladium tube 29 to a flame having an excess of hydrogen. As illustrated, this is accomplished by a torch 30 which is connected with a supply of hydrogen or other gas which will burn with an excess of hydrogen. A pilot light on the torch is allowed to burn continuously and is adjusted by a manually operable valve 32 provided in a bypass connection 33. As illustrated in Figs. 1 and 3a and 3b identical stationary torch structures are provided at stations VI and XVI and XII.

When it is desired to introduce gas into the discharge device I0, the main supply line 34 connected with the torch is opened by operation of a solenoid 35 which controls a valve in conduit 34. As a means for controlling the operation of the solenoid 35 in accordance with the pressure in the device 10, I provide an electric gauge including a device 36 the interior of which is subjected to the pressure of the conduit 28, and a standard device 31 which is charged with gas to a predetermined pressure. As will be described in detail in connection with Figs. 3a and 3b the devices 36 and 31 include resistance elements which are in a bridge circuit and which responds to the pressure existing in the conduit 28 to produce a signal voltage for controlling the operation of solenoid 35. As illustrated in Figs. 1 and 2, the devices 36 and 31 of the various stations are supported from the turntable 2 by an annular ring or shelf 38 which is welded or otherwise secured at its inner edge to a plurality of uprights 39.

An alternating current supply for the rotating equipment of the machine is provided by a pair of supply lines 40 which connect with slip rings 41 and 42 mounted in spaced and insulated relation on an extension of the pedestal l. The voltage is distributed to the electrical equipment on the movable portion of the apparatus by conductors 43 and 44. A lower level of voltage is provided on conductors 45 and 48 by means of a transformer 41 energized from conductors 43 and 44.

Means for making electrical connection between the various elements carried by the movable portion of the equipment and the stationary circuits, which will be described in detail in connection with Figs. 3a and 3b are provided by a plurality of stationary slip rings or tracks 48-52, inclusive, which are supported on a suitable insulating ring 53 and which, as will become more apparent as the description of Figs. 3a and 3b proceeds, may be segmented at each station of the equipment so that the angular extent of any of the tracks may be increased in increments corresponding to the angular extent of each station simply by connecting adjacent segments together. The slip rings are engaged by suitable brush assemblies 54 to 58, inclusive, provided at each movable station cooperating with the tracks 48-52, respectively. The brush assemblies are mounted in mutually insulated relation on a support 59 which is, in turn, supported from the body of the compression fittings by supporting arms 90. As illustrated in Fig. 1, a switch is supported on the movable portion of the machine at each station. These switches, designated by the numerals 8| to I6 inclusive, are supported from the lower end of the support 59 and are arranged to be actuated in accordance with the position of the rotatable part of the machine by spring arms 11 which are secured to the switch bodies and engage at their free ends with a cam surface 18 provided on the lower edge of the insulating support 53. As will be described in detail at a later point in the specification, switches iii-16 are actuated in accordance with the position of the movable portion of the machine to control the operative position of the solenoid valve ll. Additional switches I9, and 8| are'provided at the stations VI, XII and XVI respectively of the machine for controlling the injection gas at these stations. In the particular embodiment illustrated, these switches are located at stations VI, VII and XV. As illustrated. these switches are momentarily operated each time the machine indexes by a spring arm 82 mounted at each station and carried on the support 59.

The manner in which the apparatus embodying my invention functions to control the evacuation and gas charging of the electric discharge device supported on the compression fittings I2 will be better understood by considerationof the control circuits illustrated in Figs. 3a and 3b. In Figs. 3a. and 3b certain of the parts correspond generally to parts illustrated in Figs. 1 and ,2 and these parts are designated with the same numerals. The numerals in most instances have been primed, however, since the illustration in Figs. 3a and 3b is entirely diagrammatic. Referring now to Figs. 3a and 3b the circuits above the line 83-44 are movable circuits mounted on the turntable 2, and the circuits below the line 83-84 are stationary circuits of the equipment. It will be noted that the movable circuits have been duplicated four times, corresponding to four stations of the equipment. For the particular embodiment of my invention which was successfully employed in the manufacture of hydrogenfilled discharge devices I have illustrated positions corresponding to positions VI, XII, XV and XVI of the machine since these positions illustrate the novel features of the evacuating and gas charging apparatus which I provide. It will be understood that the various steps of sintering and the like which are employed in making discharge devices may be accomplished at the intermediate stations.

Referring now to the movable circuit of positions VI, I have indicated the electric discharge device I9 as including an anode 85, a grid 99, a cathode 8'! and a filament 99. Pressure within the device I9 is communicated to the interior of an envelope 36' of a device including resistance elements 89 and 99, each having its end terminals brought out to the exterior of the envelope. A similar comparison device 31', having the envelope thereof charged to a predetermined gas pressure, is likewise provided with resistance elements 9I and 92. These elements also have their end terminals extending to the exterior of the envelope. The elements of devices 96' and 91' are connected in alternate arms of a bridge circuit and a balancing or adjusting resistor 93 is connected between adjacent end terminals of the elements 89 and 9|. Low voltage alternating current is supplied to an adjustable point on a resistor 93 and the common terminal of resistance elements 99 and 92 by conductors 94 and 95 connected, respectively, with supply conductors l5 and 46'. Piranni gauge which, as will be readily understood by those skilled in the art, provides an output voltage between terminals 99 and 91 which is a function of the pressure within the device 39 and likewise a function of the pressure within the discharge device I9. This voltage appearing across terminals 96 and 91 is impressed on the tracks 48' and 5| respectively by conductors 98 and 99. As will be described more in detail, this voltage is employed to control the operating solenoid 35 of the torch 39' which is employed for introducing gas into the device I9. As also illustrated in connection with position VI of Fig. 3a the filament 88 of the discharge device I 9' is connected with collector rings 48' and 49' and the control grid is connected with collector ring 59'. The heater element of the vacuum pump is illustrated by resistor 9', and is connected directly across the alternating current supply lines 43 and 44'. The operating coll ll of the solenoid valve is arranged to be connected in parallel with the heating element 9' and to supply conductors 43' and 44, in accordance with the position of the machine, by switch 66 which is operated by the cam strip I8. As illustrated in Figs. 3a and 3b, all of the tracks 49' to 52' are segmented so that the rings at each station are insulated from those of the remaining stations. The track 48, however. is made continuous so that the voltages applied to this ring are available at each position of the machine for control purposes.

At position VI of the machine the discharge device I9 is charged with a predetermined amount of hydrogen gas and is subjected to induction heating, first at a high'level for a predetermined interval of time and then at a lower level for a second interval. The control of the gas injection is accomplished by an electromechanical timer I99 and the control of the level of induction heating is controlled by a timer I9I. Each of the timers is identical and includes a clock-type motor I92 energized from an alternating current supply circuit I 93. The motor is mechanically coupled with a movable contact Ill to means including a solenoid-operated clutch I95 having an operating winding I99. The movable contact I94 of timer I99 cooperates with an arcuate stationary contact I94 to control the operation of a relay I91 to disable a power oscilla- The bridge circuit forms a modified.

tor employed for induction heating of the device I9 and designated generally by the numeral III. A suitable high frequency heating coil III is provided for heating the device II in accordance with the output of the oscillator III. This control is accomplished by contact II! which controls the energization of a power supply control relay I II from the alternating current supply I93. The contacts III of relay III are connected in the alternating current supp y lines II: which provide the power input to the oscillator Ill. A second contact III on the relay I811 controls the injection of hydrogen gas to the device II by controlling the energization of the operating so noid 35' or the torch 39'. This contact connects the coil with the alternating current supply lines I93. It will be apparent that the length of time that the contact I engages the fixed contact I94 determines the period that the solenoid 35' is energized, and as a result the interval during which gas is injected into the discharge device I9. Contact I99 prevents energization of the power oscillator during the gas njection and is a safety provision to prevent explosion during the gas injection operation. In a similar manner, timer III functions to change the output power level of the oscillator I99 and to efiect energization of the solenoid I I of the evacuating system. As indicated in the drawings, the movabFe contact I 94 engages the fixed contact Ill for a predetermined interval of time after the energization of the clutch solenoid I96. Contacts I 94 and I94 of the timer I 9i, when closed, connect the operating coil of control relay III across the alternating current supply circuit Ill.

Contacts II5 of relay III are arranged to shuntan adjustable resistor IIG connected in circuit with the saturating winding II! of a saturable reactor II8 which is connected in the supply line I I! for the oscillator and which, as will be readily understood. controls the magnitude of the alternating current voltage impressed on the oscillator input circuit. The saturating winding III is connected to be energized in accordance with the voltage of a direct current supply circuit II 9. As indicated, a voltage dividing resi tor III is provided for making an initial adjustment of the energization of the saturating winding I I I. In accordance with usual practice reactor H8 includes a pair of oppositely wound alternating current impedance windings I22. It will be apparent that when relay I I l is energized and contacts [I5 closed, resistor II6 will be shorted out and the saturating winding will be energized with a high direct current voltage, reducing the impedance of the windings to a minimum and operating the power oscillator at a high output level.

Simultaneously, with the reduction oi. the power output of the oscillator resulting from opening of relay Ill, it is desirable to initiate pumping out of the discharge device I9. Since this occurs at position VI. it is not possible to accomplish this by the mechanical switching operation during indexing of the machine. For this reason additional contacts I23 are provided on control relay I I4 to connect one side of the alternating current supply I93 with the track 52' when relay Ill is deenergized. This completm a circuit for the operating winding I I to the conductor 94'. Since slip rings II and 42' are energized from the same circuit as the supply circuit I93, this completes an alternating current circuit for the energization of the operating solenoid II of the vacuum pump 4 to initiate evacuation of the device I9 at the same time that the "-chine indexes, the contacts I9 of switch 19 are connected in the energizing circuit of coils I05. As illustrated in Fig. 1, switch I9 is momentarily opened by a spring arm 82 each time a station moves into position VI.

-The next position of the machine illustrated in Fig. 3a is position XII; At this position hydrogen gas is introduced into the device until a predetermined pressure is obtained. It is also desirable to drive this hydrogen into the metal parts such as the control grid so as to minimize gas cleanup in the completed device. In position XII, therefore, gas is introduced into the device under the control of an electric pressure gauge while the filament, cathode and control grid are energized. Accordingly, at position XII track 49' is connected with a source of alternating voltage for energizing the filament of device I. As indicated, tracks 48' and 49' are energized from the output of a transformer I24 having the primary winding thereof energized from the alternating current supply circuit I03 through an adjustable voltage device such as an auto-transformer I25. Track 48' is also energized from one side of the direct current circuit I I9 by conductor I29. The track 50' is energized with a direct current voltage which is positive with respect to track 48 by means of a conductor I21 which is connected through resistor I28 to an adjustable point on voltage dividing resistor I28. Resistor I29 is energized from the direct current supply lines H9 and provides a suitable direct current voltage for producin a discharge between the grid and cathode of the device I0. In position XII a second hydrogen torch 30" is provided and is arranged to cooperate with the palladium tube 19 for the injection of hydrogen into the discharge device I0. The operation of the torch 30" is controlled by controlling the energization of the operating solenoid 35" thereof in accordance with the pressure existing within the device I0. As indicated on the drawing, the winding 35" is energized in accordance with the output or an amplifier I30 which amplifies a control signal received from the output conductors 98 and 99 of the pressure bridge and is impressed on the input conductors I3I through tracks 48' and The amplifier I30 includes a discharge device I32 having the plate circuit thereof energized from the alternating current supply circuit I03. The cathode is connected with one side of circuit I03 through a conductor I33 and the anode is connected to the other side of the circuit I03 through an operating coil of a milliammeter I34, the operating winding I35 of a relay I36, conductor I31, and normally closed contact I38 of a switch 80. The switch 80 is operated as the machine indexes from one position to the next to reset the relay I38. As illustrated in the drawing, the'control grid I39 of the electric discharge device I32 is energized from the signal voltage derived from the pressure-responsive bridge includin devices 36' and 31' through a transformer I40 having an adjustable resistor I connected in the primary circuit thereof for adjusting the magnitude of the voltage signal for a predetermined pressure within the electric discharge device I0. The secondary winding of the transformer I40 has one terminal thereof connected with the cathode of the device I32 and the other terminal connected with the grid through a self-biasing circuit Including a parallel connected resistor I42 and capacitor I43.

In position XV provision is made for pumping out the hydrogen or other gas from the discharge device I0' a predetermined interval of time after the machine indexes into that position. For. this purpose an electromechanical timer I is provided. This timer is in general similar to the timers I00 and IN provided in connection with the stationary control circuit employed at position VI and includes a clock-type "motor I45, a. clutch I46 including an operating solenoid I41, a spring-biased movable contact I48 and an arcuatestationary contact I49. As illustrated, the clock motor is energized from the alternating current supply circuit I03 and the clutch operating solenoid I04 is energized from the circuit I03 through a circuit including the contacts I38 of switch 00. sures that the timer I44 is reset as the switch 80 is momentarily operated during an indexing operation of the machine. A predetermined interval of time after indexing the machine the adjustable contact I48 moves into engagement with contact I49 and completes a circuit from the upper conductor of circuit I03 to the track 52', thus completing an energizating circuit for the operating winding II of the solenoid valve controlling the communication between the vacuum pump and thedischarge device I0. This circuit is completed through conductor 44' and collector ring 42' which, as earlier stated, is energized from the same alternating current potential as the lower conductor of circuit I03. As the machine indexes into position XVI the discharge device is fully evacuated and is ready for charging to a final gas pressure at which the device I0 is to be sealed ofl. This gas charging is accomplished in the same manner as the gas charging in position XII and the output signal from the bridge circuit of the pressure gauge is impressed on an amplifier circuit which corresponds exactly with the amplifier I30 located at position XII and the corresponding parts of which are designated by the same reference numerals. When the pressure reaches a predetermined value for which the amplifier and pressure indicator bridge are adjusted the solenoid I38 operates to deenergize the solenoid 35, controlling the operation of the torch 30". At this point the manufacture of the device is complete and it is removed from the machine by sealing ofi the tribulation.

The features and advantages of my invention will be better understood by a brief consideration of the operation of the illustrated embodiment thereof with respect to one station as it moves through the various operating positions of the machine. In position I of the machine the electric discharge device to be evacuated is mounted on the compression fitting I2 and in this position the solenoid valve II is in its closed position since the switch GI, which controls the energization of the winding II of this valve, is in the open position. In positions II to V, switches 62 to 65, inclusive, are closed and solenoid valves are open and the device as a result is being evacuated. In accordance with practices well understood the metal parts of the device may be heated by an electric oven while in these positions.

When the machine indexes into position VI the metal parts are cleaned by heating in an atmosphere of hydrogen. Referring particularly to Fig. 3:1, as the machine indexes to position VI, switch I9 momentarily opens to reset the timers I00 and III. Switch 19 immediately recloses,

This connection in- 9 energizing the clutch solenoids I08 and initiating operation of the two timers. During the first portion of the interval during which the movable station is at position VI, both relays I01 and H4 are energized and as a result the power oscillator is deenergized since contact I09 is open. Contact II3 of relay II is closed to complete the energizing circuit for the operating coil 35 of the torch 30', thus introducing gas through the palladium tube 29' for a period determined by setting of the timer I00. When the movable contact I04 moves away from contact I04, relay M1 is deenergized and contact I09 closes to energize relay I I0. This relay completes the supply circuit for the power: oscillator to initiate inductive heating of the discharge device I 0. As previously indicated, relay H4 is energized and the contacts II5 thereof short out resistor II 6 which is in series with the saturating winding II! of the saturable reactor connected in the supply lines 9. As a result, the impedance of the reactor is at a minimum and the alternating voltage supplied to the oscillator is at a maximum, thus producing a high power output of the oscillator. When timer IOI times out, contacts I04 and I04 of this timer open and relay H4 is deenergized, opening contact H5 and closing contact I23. Opening of contact II5 inserts resistor H6 in the circuit of the saturating winding III to increase the impedance of the saturable reactor and decrease the output of the oscillator. At the same time contacts I23 close and complete a circuit from the upper conductor of supply circuit I03 to the track 52', thus energizing the operating coil II of the solenoid valve controlling the connection of the vacuum pump 4 with the discharge device I0. For the remainder of the period at which the particular station remains at position VI, the discharge device is heated under vacuum conditions.

In positions VII to In, inclusive, additional steps in the manufacture of the device may be accomplished in accordance with any desired schedule. When the machine indexes into position XII, the filament of the discharge device is energized with an alternating voltage appearing between tracks 48 and 49'. The grid or control member is energized with a positive direct current voltage with respect to the cathode by virtue of its connection with the track 50'. At position XII the palladium tube 29' is subjected to a hydrogen flame under the control of a pressure responsive bridge including resistance elements 89-92, inclusive, which are supported within the envelopes 36' and 31. The envelope 36' which encloses elements 89 and 90 is subjected to the pressure existing within discharge device I0, and the device 31 is charged to a predetermined gas pressure. As will be readily understood, with the elements of devices 35 and 31' connected in alternate arms of a bridge circuit as illustrated, the output voltage exists between the conductors 90 and 91 is a function of the pressure existing within the device I0. As the pressure within the device I0 increases, the conductiv ty of the resistance elements 89 and 93 within this device 36' increases to produce a voltage signal of increasing magnitude between the conductors 98 and 99. This voltage is impressed on the input conductors I3I of an amplifier circuit I30 through tracks 43 and 5| to effect closure of relay I 38 when the pressure within the device I0 is lower than that desired. As the gas pressure increases, the voltage impressed on the 10 input circuit of the amplifier increases in a direction to decrease the conductivity of the discharge device I32, causing the relay I" to drop out when the desired pressure is reached. When relay I33 drops out, the solenoid 35" is deenergized and the hydrogen flame is removed from the palladium tube 29. The discharge device I0 is subjected to continued heating in an atmosphere of hydrogen in positions XIII and XIV and for a predetermined portion of the interval during which the device is at position XV. After the expiration of this interval. determined by a timer I44 which is in general similar to timers I00 and IN, the normally open contacts I48 and I49 are closed to impress the voltage ofthe upper conductor of supply line I03 on the track I2. This completes an energizing circuit for the relay coil ll of the solenoid valve on the intake side of the vacuum pump to eil'ect evacuation of the device I0. As the machine indexes into position XVI it is immediately charged with hydrogen gas to a predetermined pressure as determined by the pressure responsive bridge and amplifier circuit associated with the hydrogen torch 30" located at position XVI. As soon as the hydrogen flame is shut oil by operation of the pressure responsive circuit, the device I 0' is removed from the machine by the operator. It should be noted that at this position of the movable support the switch I0 in circuit with the solenoid winding I1 is open and the passage between the compression fitting and the vacuum pump is closed. The machine next indexes into position I where a new device is loaded and the above operations repeated.

While I have shown and described particular embodiments of my invention, it will be obvious to those skilled in the art that changes and modifications may be made without departing from my invention in its broader aspects, and I, therefore, aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. Evacuating and gas charging apparatus comprising an evacuating pump, a conduit connected with the low pressure side of said pump and including a fitting adapted to connect with a device to be evacuated and charged with gas, a solenoid valve in said conduit, means for injecting gas into said conduit between said valve and said fitting including a wall surface of material which is pervious only to the gas to be injected, means for closing said solenoid valve, means for subjecting said surface to said gas, and means responsive to the pressure of gas within said conduit for terminating the. operation of said last mentioned means.

2. Evacuating and gas charging apparatus comprising an evacuating pump, a conduit connecting with the low pressure side of said pump and including a fitting adapted to connect with a device to be evacuated and charged with hydrogen, a solenoid valve in said conduit, means for injecting hydrogen into said conduit between said valve and said fitting including a wall surface of palladium, means for closing said solenoid valve, means for subjecting said wall surface to an atmosphere of hydrogen, and means responsive to the pressure of gas within said conduit for terminating the operation of said last mentioned means.

3. Evacuating and gas charging apparatus com. prising a movable support, a vacuum pump, a conduit carried by said support and connected at one end with the low pressure side of said pump, a solenoid valv in said conduit between said pump and the other end of said conduit, means for controlling the operative position of said solenoid valve in accordance with the position of said support, means for introducing gas into said conduit on the side of said valve remote from said pump, and means responsive to the pressure in said conduit for controlling the amount of gas admitted to the conduit.

4. Evacuating and gas charging apparatus comprising a movable support, a vacuum pump carried by said support, a conduit connected at one end with the low pressure side of said pump, a valve insaid conduit between said pump and the other end of said conduit. means for controlling the operative position of said valve in accordance with the position of said support, means for introducing gas into said conduit on the side of said valve remote from said pump, and means responsive to the pressure in said conduit for controlling the amount of gas admitted to the con duit.

5. Evacuating and gas charging apparatus comprising a movable support, a vacuum pump carried by said support, a conduit connected at one end with the low pressure side of said pump, a solenoid'valve in said conduit between said pump and the other end of said conduit and including an operating coil, means for controlling the energization of said coil to control the operative position of said solenoid valve in accordance with the position of said support, means for introducing gas into said-conduit on the side of said valve remote from said pump including a gas pervious wall and means for subjecting said wall to said gas, and means responsive to the pressure in said conduit for controlling the amount of gas admitted to the conduit.

6. Evacuating and gas charging apparatus comprising a movable support, a vacuum pump carried by said support, a conduit connected with the low pressure side of said pump and provided with means adapted to receive a device to be evacuated, a solenoid valve positioned in said conduit between said pumpand said means, an operating winding for said valve, means for controlling the energization of said winding to control said valve in accordance with the position of said movable support, and timing means for controlling the operation of said valve to effect operation thereof independently of said last mentioned means.

7. Evacuating and gas charging apparatus comprising a movable support, a vacuum pump mounted on said support, a conduit connected with the low pressure side of said pump and provided with means adapted to receive a device to be evacuated, a valve positioned in said conduit between said pump and said means, means for introducing fluid into said conduit on the side of said valve remote from said pump, means for controlling'the operation of said valve in accordance with the position of said support, means including an oscillator for inductively heating a device received by said means, and timing means controlled by the position of said support for controlling the energization of said oscillator and the introduction of fluid into said conduit by said fluid supply means.

8. Evacuating and gas charging apparatus comprising a movable support, a conduit carried by said support and connected with the low pressure side of a vacuum system, said conduit being provided with means adapted to receive a device to be evacuated, a valve positioned in said conduit, means for introducing fluid into said conduit on the side of said valve remote from the vacuum system, means for controlling the operation of said valve in accordance with the po sition of said support, means including an oscillator for inductively heating a device received by said means, a pair of timing means initiated in operation by movement of said support into a predetermined position for efiecting operation of said means for supplying fluid for a predetermined interval and for thereafter initiating operation of the oscillator, means for reducing the power output of said oscillator, and means responsive to operation of said timers for operating said last mentioned means and for operating said valve to open position.

9. Evacuating and gas charging apparatus for a device including metal parts within an envelope comprising, means for evacuating the device, means for introducing gas into the envelope after evacuation, means for inductively heating the metal parts, timing means for controlling the operation of said last mentioned means to reduce the output of said means for inductively heating and effecting re-evacuation of said device while heated by the reduced output of said means for inductively heating the metal parts.

10. Evacuating and gas charging apparatus comprising a stationary support, a movable support having a plurality of ports adapted to register with corresponding ports in the stationary support in each of a plurality of relative positions of said supports, an evacuating pump, a conduit connected with the low pressure side of said pump and including a fitting adapted to be connected with the device to be evacuated and charged with gas, a conduit connected with the high pressure side of said pump and to one of the ports of said movable support,-a solenoid valve in said first mentioned conduit for controlling communication of said pump and said fitting independently of the registration of the ports in said stationary and movable supports, said pump, said conduits and said solenoid all being carried by said movable support, means for controlling the energization of, the winding of said solenoid valve to efiect closing thereof means for injecting gas into said conduit between said valve and said fitting when said valve is closed,

and means responsive to the pressure of gas with-- in said conduit for terminating the operation of said means for injecting gas.

CHARLES T. DE GROAT.

REFERENCES CITED The following references are of record in the flle of this patent:

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